Lysis of biological specimens, for example cell lysis, is used to provide biological materials for compositional analysis. Specific biological materials may include proteins, lipids, and nucleic acids either individually or as complexes. When a cell membrane is lysed, certain organelles—nuclei, mitochondria, lysosomes, chloroplasts, and/or endoplasmic reticulum—may be isolated. Such may be analyzed using methods such as polymerase chain reaction (PCR), electron microscopy, Western blotting or other analysis techniques.
There are numerous approaches to performing lysis. For example, enzymatic approaches may be employed to remove cell walls using appropriate enzymes in preparation for cell disruption or to prepare protoplasts. Another approach employs detergents to chemically disrupt cell membranes. These chemical approaches may adversely affect the resulting product, for example degrading the bio-products being released. Consequently, chemical approaches may, in some instances, not be practical.
Yet another approach employs ultrasound to produce cavitation and impaction for disrupting the cells. Such an approach may not achieve as high a lysis efficiency as may be required or desired for many applications.
Yet still another approach employs beads (e.g., glass or ceramic) which are agitated, for example, via a vortex mixer. Such an approach successfully addresses the issues raised by chemical lysis approaches, yet improvements in such an approach are desirable.
Particular biological materials that are isolated from the interior of cells or viruses for use in a variety of analysis or testing procedures include nucleic acids. These may be isolated and used, for example, in testing for bacterial or viral infections. Nucleic acid analysis or testing for such purposes may provide improved sensitivity or may shorten the time between incidence of an infection and appearance of a positive test, compared to results obtained from more traditional antibody testing. Nucleic acid analysis or testing typically involves extraction and isolation of a nucleic acid of interest, e.g., deoxyribonucleic acid (DNA), from the biological specimens, followed by amplification reactions, such as PCR. Amplification of the isolated nucleic acid increases the sensitivity of detection and identification of the resulting nucleic acid.
Commonly used techniques for rapid extraction and isolation of nucleic acids, in particular DNA, from cells utilize membranes or beads, including magnetic beads, that are made from silica or from other materials that capture DNA nonspecifically on the basis of the polyanionic chemistry of DNA. Most such techniques rely on the use of harsh reagents, such as chaotropic salts, e.g., guanidinium hydrochloride, guanidinium thiocyanate, or proteases, to lyse cells to free the DNA. The harsh reagents used in such methods of DNA isolation are not compatible with subsequent amplification reactions. The reagents must thus be thoroughly removed, often by numerous wash steps, prior to elution and subsequent use or analysis of the isolated DNA. Even the wash steps may include reagents that are incompatible with subsequent reactions and must thus be removed. For example, washes may include alcohol which must then be removed by evaporation. Additionally, methods for isolating biological materials of interest, such as DNA, may co-isolate other biological materials that may interfere with subsequent analyses. Approaches that eliminate such manipulations, particularly the use and removal of harsh reagents or co-isolation of undesirable biological materials as contaminants in the products, could advantageously improve the efficiency of the process and the utility of the isolated product, and could thus simplify and optimize processing of cell-contained substances, in particular DNA, for such purposes.